Subject: Should the C/R bit in SSAP be preserved by DLSw ?

From: Nagi Swaminathan <[email-masked]>
Date: Wed, 19 Jan 94 15:34:20 EST

I have a simple question on the format of SSAP in  XIDFRAME exchanged on the
network.

Should C/R response bit in the XID frames received from the ring be preserved
or not when sent as XIDFRAME by DLSw ?

 Which one of the following flows is correct ?  What does 6611 do ?

 The scenario uses the connection set-up sequence between a PUT2 node and
 a PUT4 node as the example. The PUT2 node initiates the connection by
 by sending a NULL XID command.

1. C/R bit in the SSAP is preserved across the network.
   ---------------------------------------------------

PUT2             DLSW1                        DLSw2                     PUT4

NULL XID_cmd(SSAP=0x04, DSAP=0x04)
--------------> 
                 NULL XIDFRAME(SSAP=0x04,DSAP=0x04)   
                 -----------------------------> 
                                              NULL XID_cmd(SSAP=0x04,DSAP=0x04)
                                               ------------------------->

                                              NULL XID_cmd(SSAP=0x04,DSAP=0x04)
                                              <-------------------------
                 XIDFRAME(SSAP=0x04,DSAP=0x04)   
                 <----------------------------- 

 NULL XID_cmd(SSAP=0x04, DSAP=0x04)
<------------------ 
 XID_rsp(SSAP=0x05, DSAP=0x04)
 ------------------->
                  XIDFRAME(SSAP=0x05,DSAP=0x04)
                  ----------------------------->
                                                XID_rsp(SSAP=0x05,DSAP=0x04)
                                                --------------------------->

2. C/R bit is not preserved across the network.
   -------------------------------------------

NULL XID_cmd(SSAP=0x04, DSAP=0x04)
--------------> 
                 XIDFRAME(SSAP=0x04,DSAP=0x04)   
                 -----------------------------> 
                                              NULL XID_cmd(SSAP=0x04,DSAP=0x04)
                                              ------------------------->

                                              NULL XID_cmd(SSAP=0x04,DSAP=0x04)
                                              <-------------------------
                 XIDFRAME(SSAP=0x04,DSAP=0x04)   
                 <----------------------------- 

 NULL XID_cmd(SSAP=0x04, DSAP=0x04) (Note 1)
<------------------ 
 XID_rsp(SSAP=0x05, DSAP=0x04)
 ------------------->
                  XIDFRAME(SSAP=0x04,DSAP=0x04)
                  ----------------------------->
                                                XID_rsp(SSAP=0x05,DSAP=0x04)
                                                --------------------------->

 Note 1:
 ------
 If case 2 is correct, how can the DLSw1 decide whether to put the XID
 through as a command or a response (see Alan Bartky's message of 7/19/93
 and Steve Klein's message of 8/12/93)? 

Regards..

Nagi.

---

From: Gilbert Moineau <[email-masked]>
Date: Thu, 20 Jan 94 09:41:00 PST

If my understanding is correct, the "frame direction" field is set to 01 for 
a cmd and 02 for a resp.

 ----------
From: Nagi Swaminathan
To: aiw-sig-dlsw-connect
Subject: Should the C/R bit in SSAP be preserved by DLSw ?
Date: Wednesday, January 19, 1994 3:34PM

Should C/R response bit in the XID frames received from the ring be 
preserved
or not when sent as XIDFRAME by DLSw ?

PUT2             DLSW1                        DLSw2                     PUT4

                                              NULL
XID_cmd(SSAP=0x04,DSAP=0x04)

                                              NULL
XID_cmd(SSAP=0x04,DSAP=0x04)
                                              <-------------------------
                 XIDFRAME(SSAP=0x04,DSAP=0x04)
                 <-----------------------------

                                              NULL
XID_cmd(SSAP=0x04,DSAP=0x04)

                                              NULL
XID_cmd(SSAP=0x04,DSAP=0x04)
                                              <-------------------------
                 XIDFRAME(SSAP=0x04,DSAP=0x04)
                 <-----------------------------

 Note 1:
 ------

Regards..

Nagi.